Where new neurons come from

The brain has come alive with the sightings of stem cells, but the molecular handles on those cells are few. On page 169, Belachew et al. identify and characterize a new population of neural stem cells (NSCs) that can generate neurons in the postnatal mouse brain.

In previous work, the researchers identified cells that express CNP in transgenic mice using a CNP-GFP marker. CNP is made in immature oligodendrocytes, so it is not surprising that the GFP-positive cells also express the proteoglycan NG2, which is also found in oligodendrocytes. But NG2⁺ cells are also present in parts of the CNS that contain NSCs, and are the major cell type that continues to divide in the adult CNS. The significance of these facts has remained unclear, as...